JP5676255B2 - Thin film detector for presence detection - Google Patents

Description

  The system can be used for the determination of various parameters such as the velocity, position and / or number of objects and the presence and / or real-time imaging, motion detection of objects, including inanimate and living objects. It relates to transducers for presence detection, motion detection, real-time imaging, etc. using ultrasonic transducers, including thin film ultrasonic transducers and arrays.

  Transducers have found wide application such as sensors for motion and presence detection. The main driver is not only to increase lamp life, but also to turn on / off lights as needed to save energy in office buildings and homes. The motion / presence sensor market is estimated to grow rapidly. In this growing area, a compact, low cost and thin (almost invisible) sensor with minimal false detection or triggering is desired. Such sensors are more intelligent, for example to allow detection of the number and position of people in a room as well as detection of the movement and direction of people in the room. desirable. Furthermore, transducers that operate at low power to enable wireless operation are also reasonable.

  Ultrasonic transducers are also attractive as sensors for other applications, such as outdoor control, for example locally dimming or turning lights on and off in cities, buildings, streets and the like. They can also be applied for intruder detection, which automatically switches on the monitoring device.

  Current motion sensors include ceramic ultrasonic motion detectors and passive infrared (IR) detectors based on pyroelectric ceramic devices. Such conventional infrared devices are very large and are typically mounted on the ceiling of a room. The patent document DE 4218789 by Klee et al. Discloses a micromachined pyroelectric detector and is hereby fully incorporated by reference. The IR sensor detects the movement of a moving person or a person from the change in the received infrared energy. The disadvantages of these pyroelectric IR detectors include the need for a line of sight for proper detection that is clear and should not be disturbed. Furthermore, IR detectors are easily disturbed by direct sunlight and changes in ambient lighting and are sensitive to smoke and heat, thus providing false alarms.

  To minimize false alarms or triggers, an ultrasonic transducer is mounted next to the passive infrared detector and a combination of pyroelectric passive detector and ultrasonic detector is used. Such composite devices are even larger than typical IR detectors and have a typical size of 11 cm in diameter and 3.5 cm in height. FIG. 1 shows a typical transducer radiation pattern 100. As shown in FIG. 1, in general, the transducer transmits a fairly narrow beam 110 and thus has large invisible regions 120, 130.

  To reduce or eliminate invisible areas, a transducer array is provided, where the signals from the transducers or elements of the array are individually used to shape and steer the ultrasonic beam transmitted from the array. Controlled. This makes it possible, for example, to detect the position of people by scanning through a room or area. It is also possible to focus the beam using a transducer array, which improves resolution and signal-to-noise ratio. Ultrasound arrays can also detect and form ultrasound images using accompanying electronic circuitry.

  Such an ultrasonic sensor is also assumed to be a vehicle airbag control for turning on / off a passenger airbag depending on the detection of the presence or absence of a passenger. Other applications of the transducer include measuring distance. In addition, such transducers may also be of interest for automotive purposes, such as passenger occupancy sensors, due to airbag on / off operation. Further, an ultrasonic transducer is described in US Pat. No. 6,549,487 by Guartieri, where an electronically steered ultrasonic beam is used to measure the range, angular range and angular direction of an object. As is used in collision prevention or protection systems, this patent is hereby fully incorporated by reference. The ultrasonic receiver receives acoustic waves reflected from the object for processing to determine information such as the range, width, size and direction of the object. These systems are typically made from separate single transducers.

  Piezoelectric ultrasonic sensors on silicon diaphragms are known, as described in a paper by Kaoru Yamashita named “Improvement of sensitivity of diaphragm type ultrasonic sensors by complementary piezoelectric polarization” (Yamashita). This paper is fully incorporated herein by reference. In addition, a paper by Valentin Magoli entitled “Ultrasonic Sensors in Air”, which is fully incorporated herein by reference, is emitted for distance detection and object recognition based on echoes reflected from the object. An intelligent ultrasonic sensor is described which includes a piezoelectric ultrasonic transducer operated as a phased array with electronic steering of the beam.

  As noted in Yamashita's paper, 3D imaging devices using air-borne ultrasound are used for vehicle control, object detection for autonomous robots, and activity support for visually impaired and inspection robots. used. As noted, the ultrasonic measurement of air is effective against electromagnetic waves including millimeter waves and light of accurate distance measurement in the range of less than a few meters due to the appropriate low propagation speed of ultrasonic waves. have.

  US Pat. Nos. 6,515,402 and 6,548,937, both assigned to the assignee by Clay et al., Are hereby fully incorporated by reference and are also described in Yamashita. Thus, an array of ultrasonic transducers with electrodes on either or one side of the piezoelectric layer is described. Such a transducer has a substrate that is micromachined to form an opening.

FIG. 2A shows an ultrasonic transducer 200 having a silicon substrate 210 on which a film 220 is formed as described in US Pat. No. 6,548,937. A barrier structure 230, such as a TiO ₂ layer, is formed on the film 220. A piezoelectric layer 240 is formed on the barrier layer 230. The first and second electrodes 250 and 255 are disposed at both lateral ends of the piezoelectric layer 240 for the laterally polarized operation of the piezoelectric layer 240. In addition, a portion of the substrate 210 is removed to create an opening 260 for exposing the membrane 220 at an appropriate location with respect to the piezoelectric layer 240 and the electrodes 250, 255. In order to manufacture such an array of ultrasonic transducers, several openings are created for the creation of several films on a single silicon substrate. The film 220 exposed by the opening 260 can vibrate due to the opening 260 (eg, upon application of an AC voltage).

  In particular, application of an AC voltage to the electrodes 250, 255 through the first and second current supply contacts 270, 275 excites the piezoelectric layer 240 into longitudinal vibration of the surface of the piezoelectric layer 240. Changes in the length of the piezoelectric element cause the membrane 220 to excite vibration. The electrodes 250 and 255 may be the interdigital electrodes 250 and 255 shown in FIG. 2B.

  FIG. 2C shows an ultrasonic transducer 200 ′ in which electrodes 250 ′, 255 ′ are formed on both sides of the piezoelectric layer 240, as described in US Pat. No. 6,515,402 and Yamashita paper. . Both transducers 200, 200 ′ shown in FIGS. 2A, 2C require the opening 260 to be made in place by removing a portion of the substrate 210, such as by bulk micromachining techniques or pattern lithography. This is time consuming and increases the cost of manufacturing such a transducer array. In addition, the substrate must be aligned to create the opening at the proper location, which not only introduces additional errors, but also increases manufacturing time and cost, and thus reduces yield. In addition, as explained in the Yamashita article, SOI (silicon on insulator) wafers are typically used, which are relatively expensive, where the films are silicon (2 μm) and silicon oxide. (0.4 μm).

  Note that the electric field is between the two opposing electrodes 250 ′, 255 ′ of FIG. 2C. This electric field is perpendicular to the piezoelectric layer. In contrast, the electric field between two adjacent electrodes 250, 575 of FIG. 2A is in the plane of the piezoelectric layer 240 or parallel to that plane. By providing closely spaced electrodes, typically interdigital, as shown in FIG. 2B, less voltage at just two electrodes for each membrane will produce the desired electric field. Needed.

Of course, in addition to using aerial ultrasound for imaging, ultrasound is also applied in fluids and solids and used for imaging such as medical acoustic holography and submersible imaging, see here A thin ferrofilm is used as described in US Pat. No. 6,323,580 by Bernstein (hereinafter referred to as Bernstein), which is more fully incorporated herein by reference. In Bernstein, the interdigital electrode is formed only on one of the ferrodiaphragms formed on the Al ₂ O ₃ insulator layer on the silicon film structure layer. The silicon film is on an SiO ₂ or Si ₃ N ₄ etch stop layer formed on a silicon substrate. The silicon substrate is selectively etched (up to a SiO ₂ or Si ₃ N ₄ etch stop layer) to form an opening under the silicon film. It should be noted that not only an additional Al ₂ O ₃ layer is applied, but expensive SOI wafer technology is used, further increasing processing time and cost. Similar to the opening 260 described in connection with FIGS. 2A and 2B, the Bernstein opening also provides an appropriate opening, for example two-side lithography and alignment, for example at a desired position under the electrode. The cost is further increased because it is formed from selective substrate removal, such as by etching and micromachining that needs to be done.

Other micromachined transducers are described in the paper entitled “Ultrasonic Radiation Performance of Piezoelectric Micromachined Ultrasonic Transmitter” (referred to as one) by Jehong Wang et al., Which is hereby fully incorporated by reference. It is. This transducer also requires substrate alignment and micromachining to form aligned openings in the substrate. In one paper, the film is a SiO ₂ etch stop layer formed between the Si ₃ N ₄ film and the Si substrate, and is formed of Si ₃ N ₄ .

  Thus, an improved miniature that is thinner, less large, flexible, less expensive due to reduced steps and / or reduced alignment requirements, easier to manufacture but still has high electroacoustic performance・ There is a need for sensors. Integrating other functions such as infrared detection would allow even further miniaturization.

  One object of the system and method presented herein includes the disadvantages of conventional sensors, including providing a sensor with a combined ultrasound and pyroelectric detector for detecting ultrasound and / or infrared signals. It is to overcome this point.

  According to exemplary embodiments, the Doppler effect can be used to detect the presence or movement of objects including, for example, inanimate and living objects, as well as various such as object speed, direction of movement, position and / or number For the determination of various parameters, for example, transducers and arrays of transducers are provided that are used for real-time imaging in air as well as fluids and solids. In one embodiment, the transducer has a film formed on the front substrate, and a piezoelectric layer is formed on the film in an active portion and a peripheral portion adjacent to the active portion. The If necessary, the piezoelectric layer is patterned. A patterned conductive layer including first and second electrodes is formed on the piezoelectric layer. In addition, a rear substrate structure is provided having a support located in a peripheral portion adjacent to the active portion. The height of the support is greater than the combined height of the patterned piezoelectric layer and the patterned conductive layer. Many transducers are connected to form an array, where, for example, a controller controls the array, such as steering the beam of the array for presence detection or motion detection and / or imaging, and so on. Supplied to process the received signal.

  Various sensors are provided on the flexible foil to form a flexible sensor that is formed into any desired shape. In addition, different types of sensors or detectors can be combined or integrated into a single multi-sensor such as multiple sensors including combined ultrasonic and pyroelectric detectors for detecting ultrasonic and / or infrared signals. It may be a sensor. Sensors are used in a variety of applications such as imaging (ultrasonic and / or IR imaging) as well as motion detection or presence detection, where ultrasonic sensors are used to transmit ultrasonic and / or IR signals and / or In contrast to IR sensors that require a line of sight for operation, including reception, they do not require a line of sight for operation.

  Further areas of applicability of the present system and method will become apparent from the detailed description provided below. It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the system and method, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

  These and other features, aspects and advantages of the apparatus, system and method of the present invention will be better understood from the following description, claims and drawings.

FIG. 1 shows a measurement of the radiation pattern of a typical transducer. 2A-2C show a conventional sensor implemented in bulk micromachining. FIG. 3 shows an array of transducers according to one embodiment of the system. 4A and 4B show a transducer with electrodes on one side according to one embodiment of the system. FIG. 5 shows a transducer with electrodes on the other side according to one embodiment of the system. FIG. 6 shows an array of transducers with a back substrate according to one embodiment of the system. FIG. 7 shows an array of transducers with interdigital electrodes according to one embodiment of the system. 8A-8C show a transducer with a back substrate supported by a mount according to one embodiment of the system. FIG. 8D shows a resistance biasing network according to one embodiment of the system. FIG. 9 shows a plot of electrical impedance versus frequency for a transducer according to one embodiment of the system. FIG. 10 illustrates two ultrasonic transducers that form a flexible array of transducers on a flexible foil in an interconnect according to one embodiment of the system. FIG. 11 shows the flexibility of forming a flexible array of transducers with thin film piezoelectric elements on top mounted on silicon parts with or without electronic components according to one embodiment of the system. Figure 2 shows two ultrasonic transducer devices covered on both sides with a layer interconnect. FIG. 12 illustrates a flexible array of two or more ultrasonic transducers according to one embodiment of the system. 13A-13C show an array that includes a combination of ultrasonic and pyroelectric transducers with separately mounted circuits on a substrate according to one embodiment of the system. 14A-14C illustrate an array that includes a combination of ultrasonic and pyroelectric transducers with circuitry mounted by flip chip mounting or wire bonding according to one embodiment of the system. 15A-15C show an array that includes a combination of ultrasonic and pyroelectric transducers with integrated circuitry according to one embodiment of the system. 16A-16C illustrate an array that includes a combination of ultrasonic and pyroelectric transducers with electrodes on both sides of a piezoelectric region according to one embodiment of the system. 17A-17C illustrate an array that includes a combination of ultrasonic and pyroelectric transducers with differently doped piezoelectric regions according to one embodiment of the system.

  The following is a description of embodiments showing the above features and effects, etc., with reference to the drawings. In the following description, exemplary details such as architecture, interface, technology, element attributes, etc. are set forth for purposes of explanation rather than limitation. However, it will be apparent to one skilled in the art that other embodiments that depart from these details are still within the scope of the appended claims.

  Accordingly, the following description of particular exemplary embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or use. In the following detailed description of embodiments of the present system and method, reference is made to the drawings that form a part of the description and these drawings are through exemplary specific embodiments in which the described systems and methods may be practiced. Shown. These embodiments are described in sufficient detail to enable those skilled in the art to practice the system and method of the present disclosure, other embodiments being utilized, and structural and logical changes being within the spirit and scope of the systems. It should be understood that this can be done without departing from.

  The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present system is defined only by the appended claims. With the exception that identical parts appearing in more than one figure are identified by the same reference number, the leading digit of the reference number in the figures herein generally corresponds to the figure number. Further, for clarity, detailed descriptions of well-known devices, circuits, and methods are omitted for clarity of description of the system.

  Various embodiments of the present sensor, including piezoelectric thin film transducers and transducer arrays, are cost effective and enable efficient and miniature ultrasonic transducers / arrays. The ultrasonic transducers according to various embodiments are flat, thin ultrasonic transducers that are not larger than conventional ceramic ultrasonic transducers used, for example, for occupancy detection and / or motion detection. Other examples include ultrasound to detect various parameters such as the presence, speed, direction of movement, position, movement and / or number of living and inanimate objects such as humans, animals, vehicles, etc. It includes a flat thin film transducer array that allows beam scanning and electrical steering. Such compact and thin ultrasonic transducers / arrays find a variety of applications because they do not require line of sight and do not respond to smoke and heat as opposed to infrared sensors.

  In the exemplary embodiment, a thin film piezoelectric transducer array is used for presence detection and / or motion detection, etc., where FIG. 3 shows an array 300 of thin film piezoelectric transducer elements 310. Array 300 and / or each element 310 may have any size and shape. The pitch 320 of the element 310 is selected based on the application. In order to achieve low attenuation in the air for motion detectors, the array is designed to operate at a frequency of 50-450 KHz. In order to operate at these low frequencies, the element pitch 320 is on the order of hundreds to thousands of micrometers. The pitch 320 is obtained by adding a gap 340 that separates one element from an adjacent element and a width 330 of the element.

  As shown in FIG. 3, the array is used to allow electrical steering of the ultrasonic beam for the wide coverage and reduction or elimination of blind spots 120, 130 described in connection with FIG. Such as phase shifters, delay taps, converters, etc. as described in US Pat. No. 6,549,487 to Guartieri for controlling the array and processing information received from the array 300 Are connected to a controller or processor 350 having associated electronic components. Memory 360 is also operatively coupled to processor 350 for storing software instructions or code, various data and application programs for control and operation of the array system when executed by processor 350.

  In order to achieve a high coupling coefficient of the device, which is the amount of electrical energy source converted to mechanical energy (ie, the efficiency of electromechanical conversion), instead of the electrodes on both sides of the piezoelectric material, the electrodes are piezoelectric thin films A sensor 400 as shown in FIG. 4A is provided which is processed on the same side of the element, and the element operates in a polarization direction parallel to the face of the transducer. In particular, the in-plane electric field between a pair of electrodes 430, 440 and 430 ′, 440 ′ fitted together as shown in FIG. 2B causes stress oscillation in the longitudinal direction of the surface of the piezoelectric thin film, and thus the film Lead to bending vibration. The reduced spacing between the electrodes 430, 440 allows operation at a lower voltage. In the following description, “positive” and “negative” voltages are used to indicate that the electric field of the piezoelectric material is parallel or anti-parallel to the polarization direction, respectively.

  Besides having a higher coupling coefficient, the sensor 400 also requires fewer processing steps since there is less one layer because there is no electrode layer on one side of the piezoelectric film, Allows cost-effective manufacturing of the device 400. Sensor 400 includes a film 410 formed on a substrate that is removed after formation of sensor 400 to allow movement of film 410. Piezoelectric material 420, 420 'is formed on a film 410 that is patterned if desired, for example to increase performance. In addition, a pair of electrodes 430, 440 and 430 ', 440' are formed on respective piezoelectric regions 420, 420 'of the patterned piezoelectric material.

  As shown in FIG. 4A, a positive voltage is applied to the inner edge electrodes 440, 440 ′, a negative voltage is applied to the outer edge electrodes 430, 430 ′, alternately grounded, and the piezoelectric layer extension 450 is , Resulting in a downward turn 460 in the membrane stack, as shown in FIG. 4B. Reversing the polarity of the voltage applied to the electrode pairs 430, 440 and 430 ', 440' will bend the membrane stack upward. A voltage pulse or some alternating current (AC) signal applied to the piezoelectric layer causes ultrasonic waves reflected from the object for detection of the object.

  The operating principle of the membrane transducer is illustrated in FIG. 4B where the basic bending mode is shown. Membrane displacement 404 results in bends in areas 401, 401 ′ and 402. Area 403 remains substantially unbent. Piezoelectric motion is used to bend one or more curved areas 401, 401 ′ or 402. Layered membranes will be used at least in these strainable or movable parts 401, 401 ′, 402 and will be illustrated in the following areas. A given embodiment should not impose a limit on the degree of freedom in selecting which area of the membrane is activated. For example, the stacks 440, 430, 420, 410 of FIG. 4A form the working area 401 shown in FIG. 4B. Of course, a strainable or movable stack may be placed in area 402.

  Of course, if desired, instead of one side, eg, the top side of the piezoelectric material, a pair of electrodes may sandwich the piezoelectric material 520, 525, for example as shown in the sensor 500 of FIG. , May be on both sides. In this case, voltage is supplied between the top and bottom electrode pairs 530, 540 and 530 ', 540'. When the voltage difference between the top electrode 530, 530 ′ and the bottom electrode 540, 540 ′ is positive, the extension perpendicular to the membrane and the in-plane piezoelectric layer contraction 550, 555 are indicated by arrows 560. As such, it will pull the membrane stack.

  Sensors 400, 500 are not expensive because they are efficiently formed and require less processing operations. For example, wafers and films are not made in accordance with expensive SOI manufacturing, and silicon nitride, silicon oxide, or silicon nitride and silicon oxide, as described in more detail in connection with FIGS. These are deposited using standard semiconductor processes and are not expensive. Of course, in addition to these materials, other organic or inorganic materials compatible with piezoelectric thin film processing may be used. In addition, to expose the film, as described in connection with FIGS. 2A and 2B, to remove portions of the substrate and create openings 260, for example, by patterned bulk micromachining and two-side lithography. There is no need to pattern the lower substrate 615, shown as the dotted line in FIG.

  Rather, the sensor is mounted on a die and sufficient etching is performed everywhere to remove all the underlying substrate 615. Thus, lithography or patterning is only on one side, for example to pattern electrodes and / or piezoelectric material if desired. The other side, eg, the bottom side shown in FIGS. 4A and 5, may require some lithography or patterning. Rather, sufficient etching removes the bottom or front end substrate 615 and mounts the sensor array or element on the die or back end substrate 640 as shown in FIG. 610 is performed to expose.

  Not only is a patterned etch of the substrate required, but the front side and back side masks are used to properly etch the desired portion of the substrate to obtain openings 260 (FIGS. 2A, 2C) at the appropriate locations. Since there is no need for alignment, costs and manufacturing time are reduced. This not only reduces processing time and cost, but also increases yield by eliminating alignment errors and eliminating the processing problems of fragile perforated substrates. Furthermore, as shown for example in FIGS. 4A, 6 and 8A, if the electrode is only on one side of the piezoelectric material, ie there is no electrode on the other side of the piezoelectric material, one less layer Is needed to reduce manufacturing time and cost.

  The basic module of a piezoelectric thin film transducer is a stack of thin film films, as indicated by reference numerals 410 and 510 in FIGS. 4A and 5A and 610 in FIG. 6, respectively. Illustratively, the films 410, 510, 610 are formed from silicon nitride, silicon oxide or a combination of silicon nitride and silicon oxide. The films 410, 510, 610 are deposited, for example, in a low pressure chemical vapor deposition (CVD) process, eg, on a substrate 615 that is later fully etched to expose one side of the film. The substrate is silicon or some other suitable material. A thin film barrier layer 617 made of, for example, titanium oxide, zirconium oxide, or aluminum oxide may be provided on the top of the films 410, 510, and 610 as needed as shown in FIG.

  In the embodiment shown in FIG. 6 (related to the embodiment shown in FIG. 4A with electrodes only on one side of the piezoelectric layer), or on top of the membrane layer 610 (410 in FIG. 4A). If so, a piezoelectric film is formed on top of the barrier layer 617, processed, and patterned (if desired) to form piezoelectric regions 620, 622, 624. Illustratively, the piezoelectric film may be, for example, lead zirconate titanate, which may or may not be doped with La, but may be any other piezoelectric material. Piezoelectric layer 620 may be continuous or patterned to match the width of the working area (402 in FIG. 4B). The plurality of transducer elements 600 are arranged in a one-dimensional or two-dimensional array in which the element pitch is as small as the width 626 of the elements (also indicated by reference numeral 330 in FIG. 3). The left and right piezoelectric regions 622 and 624 shown in FIG. 6 do not have a piezoelectric function, but serve as spacers or support mounts as described below. The cavity with height 826 is filled with gas or evacuated during the bonding process depending on the application. For example, the effects of gas-filled cavities include providing better encapsulation as well as sealed packages for better reliability in harsh surroundings. The effect of having a vacuum in the cavity is a disadvantage of a stiffer membrane, but includes the free movement of the membrane, especially for air transducers. The cavity may remain open relative to the ambient to provide pressure equalization with the ambient, thus reducing or avoiding parameter shifts or drifts such as shifts in resonance frequency, sensitivity, etc. However, the open cavity is sensitive to moisture and surroundings. The choice depends on the application environment.

  In addition, one or more metallization layers are applied to one side of the piezoelectric film and patterned to form an electrode shown as strip 630 in FIG. Illustratively, a first metal layer stack, for example a thin TiW layer and an Al layer with a total thickness of about 1 μm, is formed, patterned to form a first set of electrode strips 630, 630 ′, Two metal layers are formed and patterned on the first set of electrode strips 630, 630 ′ to form a second set of electrode strips 635, 635 ′. It should be understood that the stacks or layers shown herein are, for example, a single layer or multiple layers of two or more materials formed of alternating layers. The second metal strips 635, 635 ′ are, for example, a metal layer stack of Ti and Au layers having a total thickness of about 1 μm. Of course, any suitable combination and type of metals can be used to form the electrodes, for example including only one metal stack from a stack of Ti and Au. The patterning of the piezoelectric thin film and the metal layer is by any suitable method, such as a well-known lithography method, using a photoresist layer and etching.

  At the opposing edges of each array element or piezoelectric region, the metal layer may be thicker, increasing the height of the surrounding metal strip, increasing the height from about 200 nm to 2 μm or higher, for example up to 20 μm. In order to form a supporting mount 660, 660 ′ having other metal layers 650, 650 ′ formed on the previously formed metal strip. The other metal layers 650, 650 ′ may be any suitable combination and type of Ti and / or Au or metal.

  As described in more detail in connection with FIGS. 8A, 8B, thickened end or peripheral metal layers (with additional or other metal layers 650, 650 ′) are also provided as support mounts 660, 660 ′. The rear end substrate 640 is mounted on these mounts. In particular, at the top of the device 600 shown in FIG. 6, ie, on the rear end substrate on the peripheral metal strips or support mounts 650, 650 ′ of the piezoelectric regions 620, 622, 624 or opposing edges of the array elements. The 640 is mounted by ultrasonic bonding using a suitable contact metal such as, for example, Ti / Au. Of course, any other coupling scheme such as thermocompression bonding may be used. The back end substrate 640 is, for example, silicon and may be mounted by any other bonding technique using any suitable bonding agent, where the first of the metal layers 650, 650 ′ and electrode strips 635, 635 ′. Both sets of two can be Au and are very suitable for ultrasonic coupling with each other.

  The peripheral metal strip or support 660, 660 ′ on which the rear end substrate 640 is mounted has a thickness of 0.5-30 μm above the piezoelectric layer. Of course, instead of forming other metal strips 650, 650 'over the peripheral metal strips 635, 635' to increase their height, other metal strips 650, 650 'are applied to the rear end substrate 640. In this case, the rear end substrate 640 is mounted on top of the peripheral metal strips 635, 635 ′, where a simple bonding of the metal (650) on the metal (635) is performed, in the case of ultrasonic bonding In this case, Au is suitable for both the metal layers 650 and 635. Of course, if desired, a desired height support mount was formed on the rear end substrate 640, and such support mounts on the rear end substrate 640 were formed on top of the membrane 610 or on the membrane 610. It may be bonded to the top of a suitable layer.

If desired, in an alternative stack, a groove is formed in the region where the piezoelectric film 610 is acting in the alternative stack to achieve a very large gap 826 between the rear end substrate 640 and the piezoelectric transducer region. 640 may be carved. To accomplish this, the metal regions 650 and 650 ′, such as the thin Ti and Au layers on top of the back end substrate 640 (eg, can be eg a Si substrate with a ₂ μm thick SiO ₂ layer) After depositing and patterning metal regions 650 and 650 ′, dry etching process steps for SiO ₂ and Si are applied to regions where Ti / Au is not deposited. In addition to the dry etching procedure, wet etching techniques for SiO ₂ and Si may also be applied. The SiO ₂ and Si patterning makes it possible to achieve gaps from several micrometers to tens of micrometers between the piezoelectric transducer and the back end substrate 640.

  The rear end substrate 640 is a silicon substrate with or without an integrated electronic component, glass substrate or some other substrate. The mounted rear end substrate 640 may include a Si device having integrated electronic components, transistors, passive elements, and the like. For example, openings or via holes may be provided in the back end substrate 640, for example, to allow high element number interconnections for one-dimensional and / or two-dimensional arrays.

  A front or lower silicon substrate 615 carried under a transducer array indicated by dotted lines 615 (on which various layers, for example films, barrier layers, piezoelectric layers and metallization layers are formed and patterned) ), After forming and patterning the various layers, is fully or partially etched to thicken the metallized region at the edge of the array element and mount the back substrate 640 thereon. The front or lower silicon substrate 615 is completely or partially etched by, for example, wet chemical etching, dry etching, grinding and / or polishing, or a combination thereof. It is noted that neither the use or alignment of bulk micromachining or lithographic etching of the front or lower substrate 615 is required since it is not patterned, but rather is almost completely removed within the active array region. I want. That is, two-side lithography is not necessary. This reduces manufacturing time and costs.

  As described in connection with FIG. 3, a plurality of elements 310, ranging from a single element to tens, hundreds or even thousands of elements of the same and / or different sizes and / or shapes, are provided to the array 300. The For example, to operate the device at a frequency of 50-450 KHz, these elements are designed with a pitch on the order of hundreds to thousands of micrometers. An example design for a transducer array 700 operating at 200-300 KHz is shown in FIG. 7, and a cross-section of element 710 is shown in FIG. 8A. It should be understood that any other design that allows effective operation of the transducer at these low frequencies is possible, such as, for example, circular membranes or elements and arrays of some shape.

  In order to still achieve the desired resonant frequency of the device in the range of approximately 50-450 KHz while allowing operation at low voltages, the transducer element 800 has a pitch 626 of 400-1500 μm, as shown in FIG. 8A. This is a design associated with FIG. 4A in which the interdigital electrodes 840, 845 are formed only on one side of the piezoelectric layer 820, similar to the interdigital electrodes 250, 255 shown in FIG. 2B.

  FIG. 8A also shows a film 830 where a piezoelectric layer 820 is formed and patterned on the film 830 to form a central active region 821, and an interdigital layer is formed on the central active region 821. Electrodes 840 and 845 having a layout are provided. Low voltage operation is achieved utilizing very small spacing between the interdigital electrodes 840, 845 and an increased number of interdigital electrodes.

  Piezoelectric material 622, 624 also remains in the peripheral region 822, 824, and a metallization layer is formed over the peripheral region 822, 824, which is the first over the electrodes 840, 845 and the piezoelectric peripheral region 622, 624. To form a metal region 860. The second metallization layer 870 is formed over the first metal region 860 using the same or different metal (as also described in connection with FIG. 6). The second metallization layer 870 extends beyond the thickness of the electrode and piezoelectric layer 820 of the active region 821, ie, the height 828 (or 828 'of FIG. 8B), the thickness of the peripheral region or support mount 822, 824, That is, the height 826 (or 826 ′ in FIG. 8B) is increased. The transducer element is mounted on the upper or rear substrate 640, for example clamped by binder, ultrasonic bonding or thermocompression bonding.

  The array of transducer elements (700 in FIG. 7 and 300 in FIG. 3) is configured such that elements having a pitch 320 (FIG. 3) of 400-800 μm are connected, for example, in parallel for beam steering and scanning. Formed. As described in connection with FIGS. 4A and 4B, film 830 is formed on a silicon nitride formed on a front or lower substrate (which is later removed as shown by dotted line 615 in FIG. 6). Layer 847 and silicon oxide layer 850 formed over silicon nitride layer 847 or a combination of silicon nitride and silicon oxide layers.

  As described, a voltage signal that applies a different sign (ie, polarity) voltage to adjacent electrodes is applied to the interdigital electrodes 840, 845, thus creating an in-plane electric field between the electrodes 840, 845. Therefore, the piezoelectric layer 820 is excited by vibration in the longitudinal direction in the plane of the piezoelectric layer 820. The change in length of the piezoelectric element excites the membrane 830 into vibration.

  Of course, instead of a design in which the electrode is supplied on one side of the piezoelectric layer, the electrode is described in connection with FIG. 5, where the patterned piezoelectric layer or region 820 ′ has two opposing electrodes 840 ′, As shown in FIG. 8B sandwiched between 845 ′, it may be supplied to both sides of the piezoelectric layer. In this case, the piezoelectric layer 820 'is patterned in a region that matches the patterned opposing electrodes 840', 845 '.

  In the embodiment shown in FIG. 8B, the piezoelectric layer 820 ′ is covered from both sides with a pair of complementary electrodes 840 ′, 845 ′ for applying a voltage. Of course, one of the electrodes of any of the embodiments shown in FIGS. 8A or 8B may be grounded. Illustratively, the bottom electrode 840 ′ is, for example, a Ti / Pt electrode and the top electrode 845 ′ is a Ti / Au electrode. Of course, any other electrode material compatible with the piezoelectric layer may be used.

  The design may be modified to match the electrical impedance of the drive electronics by using a series connection of working regions as shown in FIG. 8C representing a transducer 801 according to another embodiment. Such a design may also use thin electrodes with still acceptable resistance losses. A signal voltage is applied between the peripheral top electrodes 880, 885 that creates good electrical conductivity by adding an additional metal layer 630 that does not interfere with the bending mode of the film. Overlapping electrodes 890, 895 on opposite sides of the piezoelectric layer 620 may be floating or connected to an external small leakage voltage divider, such as a high value resistor chain. In FIG. 8C, the active portion of the piezoelectric layer 620 is divided into segments connected in series by capacitive coupling between the overlapping bottom electrode 890 and top electrode 895. Yet another variation (and applies to all examples) is to apply a DC bias voltage to enhance the piezoelectric coupling as shown in FIG. 8D. The bias voltage may be supplied to elements 880, 885, 887, and 890 via ports 892 and 894 through resistors 891 and 893. Input signals may also be supplied via ports 895, 896, for example. In this way, an electrostrictive material can also be used as the active layer 620, or a bias connection may be used for the pole of the piezoelectric material.

  Such a thin film transducer array operates at a frequency of 50-450 KHz, as indicated by plot line 900 in FIG. 9 for an independent thin film piezoelectric transducer film, where the x-axis is frequency and the y-axis is It is the real part of the electrical impedance.

  Various modifications may be provided, as will be appreciated by those skilled in the art in view of the description herein. For example, the working electrode may form a single plate capacitor at the center of the film or at the edge of the film. Alternatively, a single plate capacitor may be divided into smaller areas connected in a series configuration that matches the operating voltage of the drive circuit. Each of the transducers, sensors, and systems described above may be utilized in conjunction with other systems.

In addition, according to WO 03/092915, U.S. Pat. No. 6,515,402, U.S. Pat. No. 6,548,937 and Fraser et al. A variety of materials may be used in different layers as described in WO 03/092916.
For example, the barrier layer may be formed from one or more of the _{following: TiO 2, Al 2 O 3} , HfO 2, MgO and / ore _ZrO 2.
Piezoelectric thin film materials include:
1. PbZr _x Ti _1-x O ₃ with or without doping (0 ≦ x ≦ 1). The doping has La, Mn, Fe, Sb, Sr, Ni or a combination of these dopings.
2. Pb (Zn _1/3 Nb _2/3 ) O ₃ --PbTiO ₃ , Pb (Mg _1/3 Nb _2/3 ) O ₃ --PbTiO ₃ , Pb (Ni _1/3 Nb _2/3 ) O _3- PbTiO ₃ , Pb (Sc _1/3 Nb _2/3 ) O ₃ -PbTiO ₃ , Pb (Zn _1/3 Nb _2/3 ) _1-xy (Mn _1/2 Nb _1/2 ) _x Ti _y O ₃ (0 ≦ x ≦ 1, 0 ≦ y ≦ 1), Pb (In _1/2 Nb _1/2 ) O ₃ —PbTiO ₃ , Sr ₃ TaGa ₃ Si ₂ O ₁₄ , K (Sr _1−x Ba _x ) ₂ Nb ₅ O ₁₅ (0 ≦ x ≦ 1), Na (Sr _1−x Ba _x ) ₂ Nb ₅ O ₁₅ (0 ≦ x ≦ 1), BaTiO ₃ , (K _1−x Na _x ) NbO ₃ (0 ≦ x ≦ 1), (Bi , Na, K, Pb, Ba) TiO 3, (Bi, Na) TiO 3, B _{7 Ti 4 NbO 21, (K} 1-x Na x) NbO 3 - (Bi, Na, K, Pb, Ba) TiO 3 (0 ≦ x ≦ 1), a (Bi x Na 1-x) TiO 3- _b (KNbO _3−c ) _1/2 (Bi ₂ O ₃ −Sc ₂ O ₃ ) (0 ≦ x ≦ 1, a + b + c = 1), (Ba _a Sr _b Ca _c ) Ti _x Zr _1−x O ₃ ( 0 ≦ x ≦ 1, a + b + c = 1), (Ba _a Sr _b La _c ) Bi ₄ Ti ₄ O ₁₅ (a + b + c = 1), Bi ₄ Ti ₃ O ₁₂ , LiNbO ₃ , La ₃ Ga _5.5 Nb 0.5 _{. 5} O ₁₄ , La ₃ Ga ₅ SiO ₁₄ , La ₃ Ga _5.5 Ta _0.5 O ₁₄

  Further, various stacks or layers forming support mounts 822, 824 (eg, as shown in FIG. 8B) may be formed on one or both of piezoelectric layer 622 and back substrate 640. For example, two metal layers 630, 635 are formed on the piezoelectric layer 622, and one metal layer 650 is formed on the back substrate 640 for bonding with the second metal layer 635. Alternatively or additionally, the first metal layer 630 is formed on the piezoelectric layer 622, and the two metal layers 650, 635 are formed on the back substrate 640, where the second metal layer 635 is the first metal layer 635. Of the metal layer 630.

The various stacks or layers forming the support mount (eg, support mounts 822, 824 shown in FIG. 8B) include one or more of the following materials, where the first metal layer 630 is the piezoelectric layer 622's. A second metal layer 635 is formed over the first metal layer 630. Another metal layer 650 is formed on the back substrate 640 as shown in Table 1. For example, in the first row of Table 1, the Ti layer is formed on the piezoelectric layer 622 and the Au layer is formed on the Ti layer, where the Ti and Au layers form the first metal layer 630. An embodiment is shown. The other Au layer is formed as a second metal layer 635 on the Au layer of the first metal layer. A Ti layer is formed on the rear substrate 640. An Au layer is formed over this Ti layer, where these Ti and Au layers form an additional or other layer 650 on the back substrate 640. Next, the Au layer of the other layer 650 is bonded to the Au layer of the second metal layer 635.

Of course, any other combination of metals and metal stacks may be used to form the various layers. Further, instead of forming only the other layer 650 on the back substrate 640, the second metal layer 635 is also formed on the other layer 650 (instead of being formed on the first metal layer 630). May be. After forming the stack of layers 650, 635 on the back substrate 640, the second metal layer 635 is bonded to the first metal layer 630 formed on the piezoelectric layer 622. In this case, the second metal layer 635 will overlap the other layer 650 (eg, instead of overlapping the first metal layer 630 as shown in FIGS. 6 and 8B). Table 2 shows various embodiments of layers where another layer 650 is formed on the back substrate 640 and a second metal layer 635 is formed on the other layer 650.

  As shown in Table 2, one of the other layers 650 forms a first Au layer, and then as a second layer 635 (on top of the first Au layer) a second Au layer Note that instead of forming a single thick Au layer may be formed on the Ti layer (of the other layer 650) formed on the back substrate 640. As in the case of the first row of Table 1, in the embodiment shown in one row of Table 2, the Ti layer is formed on the piezoelectric layer 622 and the Au layer forms the first layer 630. Is formed on a Ti layer, which is bonded to a thick Au layer formed on the Ti layer of the rear substrate 640. Of course, any other combination of metals and metal stacks may be used to form the various layers found in Table 2.

  In certain applications, different shapes of the transducer array are desirable. For example, U.S. Patent Application Publication No. 2007/0013264 by Virala, which is fully incorporated herein by reference, describes a capacitive membrane ultrasonic transducer array formed on a slab of a carrier substrate of semiconductor material. The two slabs of the substrate are separated or connected by a thinner substrate bridge that allows bending. Separated or thinly connected slabs are positioned along a rigid curved surface that forms a curved array. The slabs are connected by conductive interconnects that are flexible enough to withstand the degree of curvature. Although the desired shape is achieved by placing the slab on a curved surface, the thin bridge or conductor connecting the slab is fragile. Furthermore, the curved surface itself is hard and not flexible.

  In one embodiment of the device and system, an improved or truly flexible array of transducers is provided that is better protected and formed into the desired shape without the need for a rigid surface itself. . For example, the array 300 shown in FIG. 3 includes at least one thin film flexible ultrasonic transducer configured as at least one omnidirectional motion and presence detector. Instead of or in addition to the flexible ultrasonic transducer, at least one thin film flexible pyroelectric sensor is provided. The combination of flexible ultrasonic and pyroelectric sensors utilizes two types of sensors, i.e., pyroelectric and ultrasonic sensors, where the pyroelectric sensor, for example (requires a series of views for IR signal detection). Based on the detection of temperature changes using infrared (IR) signals (which have the disadvantage of), the ultrasonic sensor detects ultrasonic signals around the barrier but does not require a direct line of sight, so Less out of office or false alarms are provided.

  The flexibility of the array of ultrasonic and / or pyroelectric transducers allows the realization of arrays of various shapes. Such a flexible transducer array is formed into any desired shape, for example a conical shape, and mounted on the ceiling. This allows omnidirectional transmission and detection of ultrasound and / or IR signals.

  Embodiments are realized that include a flexible array of transducers of some type, such as, for example, a ceramic piezoelectric element as shown in FIG. 10 and / or a thin film transducer as shown in FIGS.

  In particular, FIG. 10 shows one embodiment of a flexible array 1000 of transducers 1010 having a ceramic piezoelectric element with a layer of piezoelectric material 1020 sandwiched between two electrodes 1030, 1040. Of course, if desired, the electrodes may be located on only one side of the piezoelectric material 1020, similar to that described above in connection with FIGS. 2A, 4A, 6 and 8A.

  As shown in FIG. 10, transducer 1010 is mounted, for example as an array of rows and columns, on a flexible carrier 1050 having interconnects shown as dotted lines 1060 which are wire bonds or patterned conductive paths. . Interconnect 1060 interconnects the electrodes or other desired elements such as for connection to power supplies, electronics, controllers, transistors, switches, passive or active devices, and the like. The flexible ultrasonic transducer array 1000 enables the realization of sensors with any desired shape for omnidirectional motion detection, including thin film ultrasonic and / or pyroelectric transducers. The transducers 1010 need not be flexible and are separated by a gap 1070 that allows movement of the flexible foil 1050 and allows the array 1000 to be shaped into any desired shape. It may be simply mounted, such as coupled to 1050.

  Note that the transducer 1010 of the embodiment shown in FIG. 10 does not include a membrane and the piezoelectric slab 1020 cannot bend the flexible carrier 1050. The transducer array 1010 is flexible because of the flexible carrier 1050, but the stiffness of the flexible carrier 1050 is typically too low to act as a good membrane. However, if desired, symmetry fracture may be introduced during manufacturing, for example, so that the in-plane stress is converted into a bend by pre-bending. Further, if the acoustic impedance does not match, for example, the piezoelectric material 1020 is harder than water or air, an optional matching layer 1075 may be provided to the lower electrode 1030 shown in FIG. . In addition, an intermediate rigid layer may be provided to increase bandwidth and facilitate energy transfer. Of course, a mechanical transformer such as a curved membrane may be used.

  FIG. 11 shows another embodiment of an array 1100 where two ultrasonic transducer devices with thin film piezoelectric elements on the top side mounted on a silicon portion with or without electronic components are shown. The ultrasonic transducer device is covered on both sides with a flexible layer shown as reference numerals 1150, 1155. The flexible piezoelectric ultrasonic transducer array 1100 is realized by the described thin film processing. In FIG. 11, two thin film piezoelectric ultrasonic transducer elements are shown as reference numbers 1110, 1120. Of course, any desired number of transducer elements may be included in an array of any desired configuration or topology, for example, having an equal or different number of rows and columns. Thin film processing is applied to realize a flexible ultrasonic transducer array. Alternatively or additionally, a flexible capacitive micromachined ultrasonic transducer array may be realized. The same techniques described above associated with thin film flexible ultrasonic detectors are used to implement a thin film flexible pyroelectric detector.

  In particular, the embodiment of the flexible array 1100 shown in FIG. 11 has a thin film ultrasonic transducer in which two transducers 1110, 1120 are shown. Transducers 1110, 1120 are surrounded on both sides by first and second flexible layers 1150, 1555. FIG. 11 includes a semiconductor portion, such as a silicon (Si) portion 1130 with or without integrated electronic components, and an interconnect structure 1132 embedded in a dielectric layer on top of the silicon (Si) portion 1130. A flexible transducer array 1100 with two transducers 1110 and 1120 is shown. The interconnect line 1140 for the different transducer elements 1142 has, for example, a redistributed interconnect layer based on electroplated gold (Au). For example, a thin film 1186 comprising silicon nitride and / or silicon oxide is provided. A piezoelectric thin film layer 1184 is formed on the film 1186. For example, a metallization layer 1182 comprising titanium (Ti) and / or Au may be applied, for example, to form a contact for mounting the piezoelectric portion 1184 on the Si portion 1130 by ultrasonic bonding. . This contact 1182 may serve as a ground contact. For example, another metal contact 1188 having a Ti and / or Au layer may be formed on the piezoelectric layer 1184 and used as a signal line. Of course, the embodiment shown in FIG. 11 is one option for connection to the signal line and ground to drive the piezoelectric element, but as will be apparent to those skilled in the art from this description, Other methods are possible.

  In addition to being flexible, the thin film ultrasonic transducer array 1100 is also protected by two flexible foils 1150, 1555 on both sides of the array. Of course, pyroelectric transducers may be used in addition to or instead of thin film ultrasonic transducers.

  FIG. 12 illustrates another embodiment of a flexible array 1200 of two or more ultrasonic transducers 1210, 1220, where each transducer is, for example, an ultrasonic transducer described in connection with FIG. 8A. The same as 800. As shown in FIG. 12, the rear substrate 1240 of each ultrasonic transducer 1210, 1220 is attached, for example, bonded to a flexible foil or polymer layer 1250. The back substrate 1240 may be any suitable substrate, for example a semiconductor material such as glass and / or silicon (Si), and not only the carrier, but also for the control and operation of eg transistors, switches, amplifiers and transducers. It may include active and / or passive elements such as desired electronic components.

  It should be noted that the rear substrates 1240 of the two transducers 1210, 1220 are not directly connected to each other. Rather, the back substrate 1240 is connected by a flexible polymer layer 1250, thus providing flexibility to the transducer array 1200 and being made to the desired shape.

  Note that transducers 1210, 1220 have a thinner back substrate 1240 compared to a transducer configured for an inflexible array, such as transducer 800 shown in FIG. 8A. Transducer elements such as membrane 1230, piezoelectric layer 1222, and electrode 1242 are mounted on a thin back substrate 1240, which is a thinned Si substrate, for example. The reduced thickness of the back substrate 1240 and the separation or gap 1260 between the substrates 1240 of the transducers 1210, 1220 improves the flexibility of the array 1200.

  In the Si substrate 1240, isolated via holes 1270 are formed for the interconnection of the transducers 1210, 1220 with various elements including power and ground. Various required elements such as passive and active elements, circuits, etc. can be processed in the back substrate 1240 or in or on the flexible foil 1250 to allow multiple levels of interconnection for signal and ground connections. Have. To achieve a flexible device, the membrane 1230 between the various transducers 1210, 1220 is separated. Instead of or in addition to a flexible ultrasonic transducer, a flexible pyroelectric thin film sensor may be formed. It should be noted that all the different techniques described above may be used to realize a combination of flexible ultrasonic transducer and pyroelectric sensor array.

  FIG. 12 also shows support mounts 822, 824 as described in connection with FIG. 8A, where support mounts 822, 824 are formed over piezoelectric region 622 and are shown in connection with FIG. In addition to the two metal layers 630, 635 described and described, it includes two metal layers 870, 860, for example similar to those described in connection with FIG. 8A. Of course, other metal layers may also be included in the support mounts 822, 824, such as, for example, an additional metal layer 650 shown and described in connection with FIG.

  A film 1230 shown in FIG. 12 is formed on the front or bottom substrate (which is later removed as shown by dotted line 615 in FIG. 6), as shown and described in connection with FIG. 8A. Various layers such as a silicon nitride layer 847 to be formed, and a silicon oxide layer 850 formed over the silicon nitride layer 847, or a combination of silicon nitride and silicon oxide layers may be included. Please keep in mind. Of course, other combinations of membrane layers having oxides, nitrides, oxide stacks or oxide and nitride stacks may be used.

  In other embodiments of the flexible transducer, the dielectric layers and interconnects may be mounted on a very thin back substrate 1240, for example a 50 μm thin Si substrate. This very thin substrate 1240 acts as a flexible substrate so that no additional flexible layer 1250 is required.

  Another embodiment provides for an array of at least one piezoelectric thin film ultrasonic transducer and / or piezoelectric transducer with at least one thin film pyroelectric sensor and / or an array of pyroelectric sensors for detecting infrared (IR). Includes combinations, which have various applications such as for motion detection and / or presence detection. Both ultrasonic and pyroelectric transducers are formed as thin films using a similar process and may be formed together at the same time or in parallel. Piezoelectric materials are used for the generation / transmission and reception / detection of ultrasound and IR signals. Of course, different piezoelectric and pyroelectric materials may also be applied. The following figures show different exemplary embodiments of composite thin film ultrasound and pyroelectric detectors.

  FIG. 13A shows an array 1300 that includes a combination of ultrasonic transducers 1310 and pyroelectric transducers 1320. Of course, instead of being arranged in an array, the composite ultrasound and pyroelectric transducers may be stand alone detectors or used with other detectors in any desired configuration. As a single element or as an array of elements, ultrasonic and / or pyroelectric transducers are processed on top of a film 1330, for example silicon nitride, silicon oxide or a combination of silicon nitride and oxide. FIG. 13A shows a silicon oxide layer 850 formed over the silicon nitride layer 847 as also described in connection with FIGS. 8A and 12. Of course, in this and other embodiments, other film materials such as Si or combinations of film stacks of Si and silicon oxide (eg, SiO 2) may be used. The effect of the silicon oxynitride layer is low specific heat and low thermal conductivity, which increases the thermal time constant of the pyroelectric device, where the temperature increase delta T relaxes to its background value.

  Integration with the thin film ultrasonic transducer 1310 next to the pyroelectric detector 1320 is also done in different versions. For example, the back substrate 1340 may only be mounted on a portion of the transducer as shown in FIG. 13A. In an alternative technique with the purpose of mechanically stabilizing a large membrane with an integrated ultrasonic transducer 1310 and pyroelectric detector 1320, the mounted back substrate 1340 may have a pyroelectric detector 1320 as shown in FIG. 13B. Where the integral ultrasonic transducer 1310 and pyroelectric detector 1320 are both covered by the back substrate 1340. Alternatively or additionally, to stabilize the large film of the integrated ultrasonic transducer 1310 and pyroelectric detector 1320, the Si substrate 210 ′ under the film 1330 (eg, a silicon nitride film) is shown in FIG. It may remain partially in the area between the ultrasonic transducer 1310 and the pyroelectric detector 1320 as shown in 13C. Of course, any desired number of ultrasonic transducers 1310 and pyroelectric detectors 1320 may be integrated together, where FIGS. 13A-13C show two pyroelectric detectors 1320, shown as reference signs A and B, respectively. Next, two ultrasonic transducers 1310 are shown.

In this example shown in FIG. 13A, a piezoelectric layer 1322 that is undoped or La or Mn doped lead zirconate titanate is processed on top of film 1330. A barrier layer 1317 is applied between the film 1330 and the piezoelectric layer 1322, similar to the barrier layer shown as reference numeral 230 in FIG. 2A and reference numeral 617 in FIG. 6, for example, titanium oxide or zirconium oxide (eg, TiO ₂ or ZrO ₂ ).

  This piezoelectric layer 1322 also serves as a pyroelectric sensor material for the pyroelectric detector 1320 that is formed and processed next to the ultrasonic transducer 1310. The effect of having a pyroelectric detector 1320 that is isolated from other elements (eg, other transducers) on the free membrane 1330 is that the elements are thermally isolated. Having a thermally isolated pyroelectric detector 1320 prevents a decrease in temperature due to heat conduction through the substrate. Piezoelectric or pyroelectric layer 1322 has a typical thickness of 1-6 μm. Piezoelectric / pyroelectric layer 1322 is patterned to prevent crosstalk between ultrasound transducer elements 1310 of array 1300 as well as between ultrasound and pyroelectric devices or elements 1310, 1320.

  The top electrode 1342, which is titanium (Ti) and approximately 1 μm gold (Au) with a thickness of approximately 50 nanometers (the electrode 1242 in FIG. 12 and / or the interdigital electrode 840 shown in FIG. 8A, (Similar to 845). However, other materials such as nickel / chromium (Ni / Cr) electrodes that provide optimal absorption of IR radiation may also be used as electrodes. Electrode 1342 is patterned to create an electrode for ultrasonic transducer 1310 as well as an electrode for pyroelectric detector device 1320. Alternatively, the electrode for the ultrasonic transducer 1310 may be made of Ti / Au to have an optimal electrode for ultrasonic bonding of the substrate die, and the electrode for the IR sensor 1320 may be formed of Ni / Cr. This Ni / Cr may be the same layer that is used as the adhesion layer for the thicker metal of the ultrasonic transducer.

  Each pyroelectric element 1320 has a top electrode fitted as shown in FIG. 2B shown as reference numeral 1342 in FIG. 13A. For the highest sensitivity, these form two sensors. One sensor is irradiated with infrared rays, for example, through a lens, but the second sensor is not irradiated. While the differential signal shows some change in infrared, the slow change in ambient temperature is canceled out. An optical system such as a Fresnel lens may be included as the optimal optical system for optimizing the signal including the signal-to-noise ratio. The pyroelectric or piezoelectric material 1322 is polarized by applying a DC (direct current) electric field at a high temperature, such as 180 ° C. When focusing on this one pyroelectric element 1320, the increase in temperature of one pyroelectric element 1320 is used for motion detection due to IR radiation. The change in temperature of the pyroelectric element 1320 becomes a change in the polarization of the pyroelectric element 1320, and thus also releases the surface charge. These charges cause a voltage that is read by the preamplifier that exhibits motion (ie, a change in temperature).

  As is well known, a lens 1380 is provided in front of the film 1330 of the pyroelectric element 1320 to receive IR radiation 1385. Lens 1380 is isolated from membrane 1330 to reduce thermal conduction and is configured to receive IR radiation 1385 from a desired direction. The ultrasonic waves transmitted or received by the ultrasonic transducer 1310 are shown as arrows 1387 in FIG. 13A.

  Different designs are possible for the desired operation. In one version, the two pyroelectric elements are designed in series and have opposite polarities. Such a dual element layout is used to heat both elements simultaneously to compensate for changes in background temperature. In addition to the dual element design shown in FIGS. 13B and 13C, other designs with a desired number of pyroelectric elements such as four elements or more may be used.

  Other devices, circuits, and electronic components may be supplied integrated with the substrate 1340. An electronic component such as an amplifier, which may be a FET (Field Effect Transistor) 1390, may be separately mounted on the board 1395 and wire bonded to a device having an ultrasonic transducer and pyroelectric sensor. One example is shown in FIG. 13A. Also other stacks of the system may be formed. For example, another example is shown in FIG. 13B, where the substrate 1340 is mounted on an ultrasonic transducer / array and further extends to be used to protect the pyroelectric sensor / array. Of course, other desired stacks may be formed. In FIG. 13C, another embodiment is that under the membrane, the front substrate 210 ′ forms a support 210 ″ between the piezoelectric ultrasonic transducer or transducer array and the pyroelectric sensor or sensor array. Removed.

  Thus, an array of detectors may include a combination of ultrasound and IR detectors using an ultrasonic detector only, an IR detector only, or a desired number of detectors or combinations of detectors, where A desired number of infrared elements are formed next to the ultrasonic elements to form a combined array used for ultrasonic and infrared transmission, detection, and imaging. Such composite ultrasonic and IR transducers are formed by thin film processing, where the electrodes are on the same side or both sides of the piezoelectric material, as previously described, eg, as described in connection with FIGS. .

  In another embodiment of the array 1400 shown in FIG. 14A, circuitry such as an amplifier 1390 may be used to implement transducer and pyroelectric elements 1310, 1320 on a carrier or front substrate 210 ′ to achieve a packaged solution system. It is mounted by the adjacent flip chip mount or wire bonding 1495. This carrier 210 ', which is generally a Si carrier, also has other elements, functions and devices such as resistors. Note that the carrier or front Si substrate 210 'is similar to the front substrate 210 shown in FIGS. 2A and 2C. In this way, as shown in FIG. 14A, a thin ultrasonic detector array and a pyroelectric detector array that are greatly miniaturized can be achieved. Similar to FIG. 13B, as shown in FIG. 14B, the rear substrate 1340 is extended and used to protect the pyroelectric sensor. Alternatively, as shown in FIG. 14C, to support the device, the front substrate 210 ′ isolates the piezoelectric ultrasonic transducer and the pyroelectric sensor as described in connection with FIG. 13C. Patterned to form support 210 ''.

  In another alternative embodiment of the transducer array 1500 shown in FIG. 15, similar to the front substrate 210 shown in FIGS. 2A and 2C, a circuit configuration such as an amplifier, such as an FET, is applied to the front Si substrate 210 ′. By integration, even further miniaturization is achieved. This has a non-integrated amplifier that is connected to or mounted to the transducer by means such as a stand-alone or flip chip mount or wire bond 1495, as described in connection with FIG. 14A. In contrast to As described in connection with FIGS. 2A and 2C, the front substrate 210, 210 ′ is used to form and pattern various layers on the carrier to implement an ultrasonic transducer and / or pyroelectric transducer. Used as a carrier. As described, portions of the front substrate are removed (eg, to form the opening 260 shown in FIGS. 2A, 2C), thus leaving the substrates 210, 210 ′. An interconnect 1515 is provided as needed, such as between the FET integrated with the front Si substrate 210 'and the electrode 1342.

  Alternatively, as described in connection with FIGS. 13B and 14B, the back substrate 1340 is not only used for mounting applications on piezoelectric transducers, but also as shown in FIG. It is also used to extend the top to protect the pyroelectric sensor. Further, as shown in FIG. 15C, the front substrate 210 ′ is patterned in such a manner as to separate the piezoelectric ultrasonic transducer and the pyroelectric sensor, as shown in FIGS. 13C and 14C.

  The above description of various embodiments showing electrodes on one side of the piezoelectric layer (referred to as the d33 mode) is shown and described in connection with FIGS. 5 and 8B-8C, where the electrodes are of the piezoelectric layer. It should be understood that it is equally applicable to embodiments operating in d31 mode on opposite sides.

  For example, in the transducer array 1600 embodiment shown in FIG. 16, the ultrasonic transducer 1610 operates in d31 mode (eg, as opposed to the previous embodiments shown in FIGS. 12-15 operating in d33 mode). To do. In the d31 mode, the electrodes that act on the piezoelectric layer are designed on opposite sides of the piezoelectric film. This design has the effect that the transducer can operate at a low voltage. The ultrasonic transducer 1610 is formed similar to that described above, as described in connection with FIGS. 2C, 5 and 8B-8C.

  In addition to the ultrasonic transducer 1610 having electrodes on both sides of the piezoelectric region 1621, in another embodiment of the array 1600 shown in FIG. 16A, the pyroelectric detector elements 1620 are opposed to the pyroelectric layer 1622. It is also treated as a plate capacitor with electrodes on the mating side. The pyroelectric IR transducer 1620 is realized by forming the first or front electrode 1642 on the film 1330 carried on the entire front substrate 210 ′ (ie, FIGS. 2C, 5 and 8B). , Before removing the portion of substrate 210 'to expose film 1330, as described above in connection with 8C). Next, a pyroelectric layer 1622 is formed on the front electrode 1642 and a second or rear electrode 1644 is formed on the piezoelectric layer 1622 and patterned if desired. The portion of front substrate 210 'is then optionally removed, such as to expose film 1330, the portion of film 1330 is optionally removed to expose front electrode 1642, and front electrode 1642 is optionally removed. Patterned. Next, the lens 1380 is provided at the portion of the front electrode 1642 where the lens is thermally isolated.

  The pyroelectric / piezoelectric regions and layers 1621 and 1622 are polarized by applying a DC electric field at a high temperature such as 100-300 ° C. (eg, 180 ° C.). The polarization of the pyroelectric / piezoelectric layers 1621, 1622 is perpendicular to the layers 1621, 1622. Two or more pyroelectric elements having opposite polarizations may be designed in series. Due to temperature changes from infrared, the polarization change of the device is a preamplifier which is an FET that is integrated on the front silicon substrate 210 'or mounted / connected to the transducer along with other desired electronic components and circuits. Read out. That is, the electronic circuit including the FET is implemented on a separate printed circuit board (PCB) and / or mounted, for example, by wire bonding or flip chip mounting on the Si carrier 210 '. As shown in FIG. 16B, in the variation of FIG. 16A, the electrode and the film under the pyroelectric layer may not be removed.

  The IR detector lens 1380 shown in the various figures is a segment of different characteristics, such as different curvature and different thickness, similar to a Fresnel lens, where each segment receives IR radiation from a particular region or zone. Note that it is typically divided into the segments of interest. The number and type of segments varies based on the coverage area, where generally a wider coverage area requires a higher number of segments. Depending on the size of the coverage area monitored for IR radiation, a typical lens used in an IR detector contains 7-14 segments. Such lenses are relatively expensive and increase in cost as the number of segments increases.

  Instead of having an expensive lens with many segments, an array of thin film sensors is used with lenses that do not have reduced segments or segments but still have a large coverage area. Thus, using an array of thin film transducers makes it easier to design the lens and reduces the thickness of the lens, thus reducing the cost as well as providing a compact device. For example, an IR motion / presence sensor for ceiling applications has four elements or sensors (quadrant device) and a lens with 14 segments, providing four times 14 or 56 detection areas. To do. Instead, the IR pyroelectric sensor includes 14 elements or sensors and the lens has only 4 segments, but still has the same number of detection areas, ie 14 times 4 or 56 detection areas.

  In other examples shown in FIGS. 17A-17C, the ultrasonic transducer 1310 operating in d33 or d31 mode uses a piezoelectric thin film layer with a dedicated composition, and the pyroelectric detector 1320 is the ultrasonic transducer 1310 Other dedicated layers having a special composition different from the composition of the piezoelectric thin film layer are used. In these embodiments of the integrated ultrasonic and pyroelectric / infrared (IR) device shown in FIGS. 17A-17C, the integrated ultrasonic transducer 1310 has La doped lead zirconate titanate. The integrated IR detector 1320 has a dedicated pyroelectric composition of lead zirconate titanate doped with La and Mn.

  One illustration or example is given in FIG. 17A. This example shows an array of pyroelectric sensors, an array of ultrasonic transducers and pyroelectric sensors, or a system of ultrasonic transducers similar to FIG. 13A. The piezoelectric ultrasonic transducer is operating in the d33 mode in this example. A piezoelectric layer 1322, for example a lead zirconate titanate layer doped with lanthanum (La), is deposited and patterned on top of a portion of the film 1330, for example silicon nitride and silicon oxide or some other film stack. Thus, it is located only in the area where the ultrasonic transducer is functioning. On the other part of the film 1330 where the pyroelectric sensor or array of sensors is located, a pyroelectric thin film layer 1722 is deposited on top of the film 1330. The pyroelectric thin film layer is, for example, a lead zirconate titanate layer doped with lanthanum and manganese (Mn).

  FIGS. 17B and 17C are similar to FIGS. 13A-13C with the modification of FIG. 17A where the mounted back substrate 1340 extends to cover the ultrasonic transducer and pyroelectric sensor as shown in FIG. 17B. An embodiment is shown. In FIG. 17C, an ultrasonic transducer region with a dedicated piezoelectric thin film material can be obtained by patterning the front substrate 210 ′, similar to that described in connection with FIGS. 13C, 14C, and 15C. Separated from.

  Finally, the above description is intended to be merely illustrative of the present system and should not be construed to limit the claims to any particular embodiment or group of embodiments. Thus, although the system has been described in particular detail with respect to that particular exemplary embodiment, numerous modifications and alternative embodiments are widely contemplated for the system as set forth in the following claims. It should also be understood that those skilled in the art can devise without departing from the spirit and scope. The specification and drawings are accordingly to be regarded in an illustrative manner and are not intended to limit the scope of the appended claims.

When interpreting the appended claims,
a) the word “comprising” does not exclude the presence of other elements or steps than those listed in a given claim;
b) “a” or “an” in front of an element does not exclude the presence of a plurality of such elements;
c) any reference signs in the claims do not limit the scope of the claims;
d) several “means” may be represented by structures or functions performed on the same or different items or hardware or software;
e) The disclosed elements may have hardware parts (eg, including discrete and integrated electronic component circuits), software parts (eg, computer programming), and any combination thereof.
f) The hardware part may have one or both of analog and digital parts,
g) unless otherwise stated, the disclosed device or part thereof may be combined or separated into other parts;
h) unless otherwise indicated, there is no intention that a specific sequence of actions or steps is required,
i) The term “a plurality” of elements includes two or more claimed elements and does not imply any particular range of the number of elements, ie, a plurality of elements may be as few as two elements, without limitation It should be understood that a number of elements may be included.
Further features of the present application are listed below.
Feature 1
A membrane configured to change shape in response to a force, a piezoelectric layer formed on the membrane, and at least two thin film transducer elements having at least two electrodes on an active portion of the piezoelectric layer; A flexible foil, wherein the at least two thin film transducer elements are first and second supports located on the peripheral side of the piezoelectric layer and on adjacent sides of the active portion, so that the first of the transducer array. A transducer array attached to the flexible foil on one side.
Feature 2
Further comprising another flexible foil on the second side of the transducer element, wherein the flexible foil and the other flexible foil substantially define the first side and the second side of the transducer array. The transducer array according to feature 1, wherein
Feature 3
The flexible foil is attached to a semiconductor substrate of the transducer element, the semiconductor substrate having a reduced thickness, and the semiconductor substrate is at least one isolation for connecting the transducer element to another element The transducer array of feature 1, comprising a via hole formed.
Feature 4
The transducer array of claim 1, wherein the at least two thin film transducer elements include a thin film ultrasonic transducer element and a thin film pyroelectric transducer element.
Feature 5
The transducer array according to Feature 1, further comprising a substrate positioned between the first support and the second support.
Feature 6
The transducer array according to claim 1, further comprising a support portion positioned between the at least two thin film transducer elements on the side of the film opposite to the piezoelectric layer.
Feature 7
The at least two thin film transducer elements include a thin film ultrasonic transducer element and a thin film pyroelectric transducer element, and the transducer array is disposed on the side of the film opposite to the piezoelectric layer, at least the thin film transducer element and the thin film pyroelectric element. The transducer array according to Feature 1, further comprising a support portion positioned between the electrical elements.
Feature 8
At least two thin film transducer elements having a piezoelectric layer sandwiched between at least two electrodes, and a flexible foil, the at least two thin film transducer elements on the first side of the transducer array A transducer array to which foils are attached and separated by gaps to enhance movement of the flexible foil and allow shaping of the transducer array.
Feature 9
A transducer array having at least two thin film transducer elements comprising a piezoelectric layer, a pyroelectric array having at least two thin film pyroelectric detectors comprising a pyroelectric layer, and at least two electrodes, the piezoelectric layer and the A device, wherein a pyroelectric layer is sandwiched between the at least two electrodes.
Feature 10
The device of claim 9, further comprising a flexible foil, wherein the flexible foil is attached to the transducer array and the pyroelectric array.
Feature 11
The device of claim 10, wherein the transducer array and the pyroelectric array are spaced apart by exposing a portion of the flexible foil to increase flexibility.

Claims (18)

  Forming a film on a front substrate; forming a piezoelectric layer on the film; and a patterned conductive layer including first and second electrodes on an active portion of the piezoelectric layer Forming a rear substrate structure having first and second supports located on adjacent sides of the active portion, wherein the first and second supports include the steps of: A method of forming a transducer comprising a piezoelectric material of a piezoelectric layer and a conductive material of first and second electrodes.   The method according to claim 1, wherein a supporting height of the supporting portion is larger than a combined height of the piezoelectric layer and the patterned conductive layer.   The method of claim 1, wherein forming the back substrate structure includes forming the support on a back substrate and attaching the support to a location adjacent to the active portion.   Forming the support includes forming at least one conductive layer on the rear substrate to form the support, and at least locally etching the rear substrate between the supports. 4. The method of claim 3, comprising a step.   The thickness of the support portion wherein forming the back substrate structure includes a portion of the piezoelectric layer and the patterned conductive layer beyond a total thickness of the piezoelectric layer and the patterned conductive layer. The method of claim 1, comprising: forming an additional layer on the support to increase the thickness; and mounting a rear substrate on the additional layer of the support.   The method of claim 1, further comprising the step of completely or partially removing the front substrate.   The method of claim 1, wherein forming the film comprises forming a silicon nitride layer on the front substrate and forming a silicon oxide layer on the silicon nitride layer. .   The method of claim 1, further comprising dividing the active portion into segments connected in series by capacitive coupling between overlapping bottom and top electrodes.   9. The method of claim 8, further comprising connecting a resistor to the overlapping bottom and top electrodes to provide a bias voltage.   10. The method of claim 1, further comprising the step of forming another patterned conductive layer, wherein the piezoelectric layer is sandwiched between the patterned conductive layer and the other patterned conductive layer. The method according to one item. A film configured to change shape in response to a force; a piezoelectric layer formed on the film; and first and second layers on the active portion of the piezoelectric layer and in contact with the piezoelectric layer A patterned conductive layer including a plurality of electrodes, and a back substrate structure supported by first and second supports located on the peripheral side of the piezoelectric layer and adjacent to the active portion; The piezoelectric layer vibrates in a longitudinal direction according to an electric field between the first and second electrodes, and the first and second support portions are formed of the piezoelectric material of the piezoelectric layer and the first and second electrodes. A transducer comprising a conductive material.   The support height of the first and second support portions is the first combined of the piezoelectric layer and the first electrode when the first and second electrodes are formed on one side of the piezoelectric layer. Greater than the height, and the support height is greater than the second combined height of the piezoelectric layer and the first and second electrodes when the first and second electrodes are formed on both sides of the piezoelectric layer. The transducer according to claim 11.   The transducer of claim 11, wherein the film has a silicon oxide layer positioned on a silicon nitride layer, and the piezoelectric layer is positioned on the silicon oxide layer.   A barrier layer, wherein the film has a silicon oxide layer formed on the silicon nitride layer, the barrier layer is located on the silicon oxide layer, and the piezoelectric layer is formed on the barrier layer. 12. A transducer as claimed in claim 11 positioned above.   An array comprising the transducer of claim 11.   A sensor for presence detection comprising the transducer according to claim 11.   A motion sensor for presence detection comprising the transducer according to claim 11.   An image sensor for real-time imaging comprising the transducer according to claim 11.

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